JP6952027B2 - Message transmission / reception method and device of V2X terminal in wireless communication system - Google Patents

Description

The following description relates to a wireless communication system, and more particularly to a method and an apparatus in which a V2X (Vehicle to Everything) terminal transmits control information and a message.

Wireless communication systems are widely deployed to provide various types of communication services such as voice and data. In general, a wireless communication system is a multiple access system that can share available system resources (bandwidth, transmission power, etc.) to support communication with multiple users. Examples of the multiple connection system include a CDMA (code division multiple access) system, an FDMA (frequency division multiple access) system, a TDMA (time division multiple access) system, and an OFDMA (or)) system. There are a carrier frequency division multiple access system, an MC-FDMA (multi color frequency division access) system, and the like.

Device-to-device (D2D) communication is the setting of a direct link between terminals (User Equipment; UE) and terminals without intervention of a base station (evolved NodeB; eNB). Refers to a communication method that directly exchanges voice, data, etc. D2D communication can include methods such as terminal-to-terminal (UE-to-UE) communication and peer-to-peer (Peer-to-Peer) communication. Further, the D2D communication method can be applied to M2M (Machine-to-Machine) communication, MTC (Machine Type Communication) and the like.

D2D communication is considered as a way to solve the burden on the base station due to the rapidly increasing data traffic. For example, according to D2D communication, unlike the existing wireless communication system, data is exchanged between devices without the intervention of a base station, so that the overload of the network can be reduced. In addition, the introduction of D2D communication has the effects of reducing base station procedures, reducing power consumption of devices participating in D2D, increasing data transmission speed, increasing network capacity, load balancing, and expanding cell coverage. Can be expected.

The technical subject of the present invention is a method in which a V2X terminal transmits control information and a message, and various methods related to resource reservation.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned above are ordinary technical problems in the technical field to which the present invention belongs from the following description. It will be clearly understood by those who have knowledge.

An embodiment of the present invention is a method in which a UE receives data in a wireless communication system, in which a step of receiving control information via a channel through which control information is transmitted and a resource reservation included in the control information are reserved. The information bit includes a step of confirming the information bit related to the data reception, which simultaneously indicates whether or not the UE that transmitted the control information reserves the resource, and if the resource is reserved, the resource position. The method.

When the information bit is 0, the UE can assume that the UE that transmitted the control information did not reserve the resource.

When the information bit is a value other than 0, the UE can assume that the UE that has transmitted the control information reserves a resource and transmits data after a time interval corresponding to the information bit.

When the UE is a UE that receives data corresponding to the control information, the UE can decode the data with the same frequency resource as the frequency resource for which the data was received after the time interval.

When the UE is a UE that does not receive the data corresponding to the control information, the UE can exclude the frequency resource for which the data was received after the time interval when selecting the resource for transmission.

Resources for the control information and data corresponding to the control information may always be selected at the same time.

The control information and data corresponding to the control information may be FDM-transmitted and transmitted.

One embodiment of the present invention is a method in which a UE transmits data in a wireless communication system, in which a step of selecting an information bit related to resource reservation included in control information and a channel through which the control information is transmitted are set. The information bit is a data transmission method including a step of transmitting the control information via the data transmission method, which simultaneously indicates whether or not the UE reserves a resource and, if the resource is reserved, the resource position.

If the UE does not reserve a resource, 0 may be selected as the information bit value.

When the UE reserves a resource, a value other than 0 is selected as the information bit value, and the UE can transmit data after a time interval corresponding to the selected non-zero value.

The data transmitted after the time interval may be transmitted with the same frequency resource as the data corresponding to the information bit, and may be decoded by the UE that has received the data corresponding to the control information.

The frequency resource of the data transmitted after the time interval may be excluded when the UE that does not receive the data corresponding to the control information selects the resource for transmission.

Resources for the control information and data corresponding to the control information may always be selected at the same time.

The control information and data corresponding to the control information may be FDM-transmitted and transmitted.
For example, the present application provides the following items.
(Item 1)
A method in which a UE receives data in a wireless communication system.
The step of receiving control information through the channel through which control information is transmitted, and
Steps to check the information bits related to resource reservation included in the above control information,
Including
The information bit is a data receiving method that simultaneously indicates whether or not the UE that transmits the control information reserves a resource, and if the resource is reserved, the resource position is simultaneously indicated.
(Item 2)
The data receiving method according to item 1, wherein when the information bit is 0, the UE assumes that the UE transmitting the control information has not reserved a resource.
(Item 3)
When the information bit is a value other than 0, the UE assumes that the UE that transmits the control information reserves a resource and transmits data after a time interval corresponding to the information bit, according to item 1. Described data receiving method.
(Item 4)
The data according to item 3, wherein when the UE is a UE that receives data corresponding to the control information, the UE decodes the data with the same frequency resource as the frequency resource for which the data was received after the time interval. Receiving method.
(Item 5)
The item 3 wherein when the UE is a UE that does not receive the data corresponding to the control information, the UE excludes the frequency resource for which the data was received after the time interval when selecting the resource for transmission. Data reception method.
(Item 6)
The data receiving method according to item 1, wherein the control information and the resource for the data corresponding to the control information are always selected at the same time.
(Item 7)
The data receiving method according to item 1, wherein the control information and data corresponding to the control information are FDM-transmitted and transmitted.
(Item 8)
A method in which a UE transmits data in a wireless communication system.
Steps to select the information bits associated with the resource reservation included in the control information,
The step of transmitting the control information through the channel through which the control information is transmitted, and
Including
The information bit is a data transmission method that simultaneously indicates whether or not the UE reserves a resource, and if the resource is reserved, the resource position is simultaneously indicated.
(Item 9)
The data transmission method according to item 8, wherein 0 is selected as the information bit value when the UE does not reserve a resource.
(Item 10)
When the UE reserves a resource, a value other than 0 is selected as the information bit value.
The data transmission method according to item 8, wherein the UE transmits data after a time interval corresponding to the selected non-zero value.
(Item 11)
The data transmission method according to item 10, wherein the data transmitted after the time interval is transmitted with the same frequency resource as the data corresponding to the information bit, and is decoded by the UE that has received the data corresponding to the control information.
(Item 12)
The data transmission method according to item 10, wherein the frequency resource of the data transmitted after the time interval is excluded when the UE that does not receive the data corresponding to the control information selects the resource for transmission.
(Item 13)
The data transmission method according to item 8, wherein the control information and the resource for the data corresponding to the control information are always selected at the same time.
(Item 14)
The data transmission method according to item 8, wherein the control information and data corresponding to the control information are FDM-transmitted and transmitted.

According to the present invention, the terminal can send and receive messages in an environment where congestion control is appropriately performed.

The effects obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned above are clearly understood by those having ordinary knowledge in the technical field to which the present invention belongs from the following description. Will be done.

The drawings attached herein are for the purpose of providing an understanding of the present invention, for showing various embodiments of the present invention, and for explaining the principles of the present invention together with the description of the specification. ..

It is a figure which shows the structure of a wireless frame.

It is a figure which shows the resource grid (resource grid) in a downlink slot.

It is a figure which shows the structure of the downlink subframe.

It is a figure which shows the structure of the uplink subframe.

It is a block diagram of the wireless communication system which has a multiple antenna.

It is a figure which shows the subframe in which a D2D synchronization signal is transmitted.

It is a figure for demonstrating the relay of a D2D signal.

It is a figure which shows the example of the D2D resource pool for D2D communication.

It is a figure for demonstrating the SA cycle.

It is a figure for demonstrating DCC (distributed congestion control).

It is a figure for demonstrating one Example of this invention.

It is a figure which shows the structure of a transmission / reception device.

The following examples combine the components and features of the present invention in a predetermined form. Each component or feature may be considered selective unless otherwise stated. Each component or feature may be implemented in a form that does not combine with other components or features, or some components and / or features may be combined to form an embodiment of the present invention. .. The order of operations described in the examples of the present invention may be changed. Some configurations or features of one embodiment may be included in other embodiments or may be replaced with corresponding configurations or features of other embodiments.

In the present specification, an embodiment of the present invention will be described focusing on the relationship between data transmission / reception between a base station and a terminal. Here, the base station has a meaning as a terminal node (terminal node) of a network that directly communicates with a terminal. In this document, the specific operation that is assumed to be performed by the base station may be performed by the upper node (uppernode) of the base station in some cases.

That is, in a network composed of a plurality of network nodes (newwork nodes) including a base station, various operations performed for communication with a terminal are performed by the base station or a network node other than the base station. It is clear that. “Base station (BS)” may be replaced with terms such as fixed station (fixed station), NodeB, eNodeB (eNB), and access point (AP: Access Point). The relay may be replaced with terms such as Relay Node (RN) and Relay Station (RS). Further, the term "terminal" may be replaced with terms such as UE (User Appliance), MS (Mobile Station), MSS (Mobile Subscriber Station), and SS (Subscriber Station). Further, in the following description, the “base station” can also be used to mean a device such as a scheduling execution node and a cluster header. If a base station or relay also transmits a signal transmitted by the terminal, it can be regarded as a kind of terminal.

The cell names described below apply to transmit / receive points such as base stations (basestations, eNBs), sectors (sectors), remote radioheads (RRH), relays (relays), and at specific transmit / receive points. It may be used in a comprehensive term for distinguishing a component carrier.

The specific terms used in the following description are provided to aid in the understanding of the present invention, and the use of these specific terms has been modified to other forms without departing from the technical ideas of the present invention. May be good.

In some cases, in order to avoid obscuring the concept of the present invention, known structures and devices may be omitted, or the core functions of each structure and device may be shown in the form of a block diagram. In addition, the same components will be described with the same drawing reference numerals throughout the present specification.

The embodiments of the present invention can be supported by standard documents disclosed in at least one of the wireless connection systems IEEE802 system, 3GPP system, 3GPP LTE and LTE-A (LTE-Advanced) system, and 3GPP2 system. .. That is, any step or part not described in the examples of the present invention to clarify the technical idea of the present invention can be supported by the above standard document. All terms disclosed in this document can be explained by the above standard documents.

The following technology, CDMA (Code Division Multiple Access), FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), OFDMA (Orthogonal Frequency Division Multiple Access), SC-FDMA (Single Carrier Frequency Division Multiple Access), etc. It can be used for various wireless connection systems such as. CDMA can be embodied by radio technologies (radio technology) such as UTRA (Universal Terrestrial Radio Access) and CDMA2000. TDMA can be implemented by GSM® (Global System for Mobile communications) / GPRS (General Packet Radio Service) / EDGE (Enhanced Data Rates for GSM® Radio). OFDMA can be embodied by wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, E-UTRA (Evolved UTRA), and the like. UTRA is part of UMTS (Universal Mobile Telecommunications Systems). 3GPP (3rd Generation Partnership Project) LTE (long term evolution) is a part of E-UMTS (Evolved UMTS) that uses E-UTRA, and adopts OFDMA on the downlink and SC-FDMA on the uplink. .. LTE-A (Advanced) is an evolution of 3GPP LTE. WiMAX can be described by the IEEE 802.16e standard (WirelessMAN-OFDMA Reference System) and the advanced IEEE 802.16m standard (WirelessMAN-OFDMA Advanced system). For clarity, the following description will focus on the 3GPP LTE and LTE-A systems, but the technical ideas of the present invention are not limited thereto.

(LTA / LTA-A resource structure / channel)

The structure of the wireless frame will be described with reference to FIG.

In a cellular OFDM radio packet communication system, uplink / downlink signal packet transmission is performed in subframe units, and one subframe is defined as a fixed time interval including a plurality of OFDM symbols. The 3GPP LTE standard supports a Type 1 radio frame structure applicable to FDD (Frequency Division Duplex) and a Type 2 radio frame structure applicable to TDD (Time Division Duplex).

FIG. 1A is a diagram illustrating the structure of a type 1 radio frame. The downlink radio frame is composed of 10 subframes, and one subframe is composed of two slots in the time domain. The time required to transmit one subframe is called TTI (transmission time interval). For example, the length of one subframe may be 1 ms and the length of one slot may be 0.5 ms. One slot contains a plurality of OFDM symbols in the time domain and a plurality of resource blocks (Resource Block; RB) in the frequency domain. In the 3GPP LTE system, since OFDMA is used in the downlink, the OFDM symbol represents one symbol section. The OFDM symbol can also be referred to as an SC-FDMA symbol or a symbol interval. A resource block (RB) is a resource allocation unit and can include a plurality of consecutive subcarriers in one slot.

The number of OFDM symbols included in one slot may differ depending on the configuration of the CP (Cyclic Prefix). CP includes extended CP (extended CP) and general CP (normal CP). For example, when the OFDM symbols are composed of general CPs, the number of OFDM symbols included in one slot may be seven. When the OFDM symbol is composed of the extended CP, the length of one OFDM symbol is increased, so that the number of OFDM symbols contained in one slot is smaller than that of the general CP. In the case of the extended CP, for example, the number of OFDM symbols contained in one slot may be six. When the channel state is unstable, such as when the terminal moves at a high speed, an extended CP can be used to further reduce intersymbol interference.

When a general CP is used, one slot contains seven OFDM symbols and one subframe contains 14 OFDM symbols. At this time, the first two or three OFDM symbols in each subframe can be assigned to the PDCCH (physical downlink control channel), and the remaining OFDM symbols can be assigned to the PDSCH (physical downlink chain).

FIG. 1B is a diagram showing the structure of a type 2 radio frame. A type 2 radio frame is composed of two half frames. Each half frame is composed of 5 subframes, DwPTS (Downlink Pilot Time Slot), protected section (Guard Period; GP), and UpPTS (Uplink Pilot Time Slot), where 1 subframe is composed of 2 slots. NS. DwPTS is used for initial cell search, synchronization or channel estimation at the terminal. UpPTS is used for channel estimation at a base station and uplink transmission synchronization at a terminal. The protection section is a section for removing the interference caused by the uplink due to the multiple path delay of the downlink signal between the uplink and the downlink. On the other hand, regardless of the type of wireless frame, one subframe is composed of two slots.

The structure of the radio frame is merely an example, and the number of subframes contained in the radio frame, the number of slots contained in the subframe, or the number of symbols contained in the slots may be changed in various ways.

FIG. 2 is a diagram showing a resource grid in a downlink slot. In the figure, one downlink slot contains seven OFDM symbols in the time domain, and one resource block (RB) contains twelve subcarriers in the frequency domain, but the present invention is not limited thereto. For example, in a general CP (normal-Cyclic Prefix), one slot may contain 7 OFDM symbols, but in an extended CP (extended-CP), one slot may contain 6 OFDM symbols. Each element on the resource grid is called a resource element. One resource block contains 12 × 7 resource elements. ^{The number N DL} of the number of resource blocks included in the downlink slot depends on the downlink transmission bandwidth. The uplink slot can have the same structure as the downlink slot.

FIG. 3 is a diagram showing the structure of the downlink subframe. A maximum of three OFDM symbols at the beginning of the first slot in one subframe correspond to the control area to which the control channel is assigned. The remaining OFDM symbols correspond to the data area to which the Physical Downlink Shared Channel (PDSCH) is assigned. The downlink control channels used in the 3GPP LTE system include, for example, a physical control format indicator channel (Physical Control Forum Indicator Channel; PCFICH), a physical downlink control channel (Physical Downlink Control Channel; PDCCH), and a physical HARQ channel. There is an automatic repeat request Indicator (PHICH) and the like. The PCFICH contains information about the number of OFDM symbols transmitted in the first OFDM symbol of the subframe and used for control channel transmission within the subframe. PHICH includes a HARQ ACK / NACK signal as an uplink transmission response. The control information transmitted by PDCCH is referred to as downlink control information (DCI). The DCI includes uplink or downlink scheduling information and includes uplink transmit power control instructions for any terminal group. PDCCH includes resource allocation and transmission format of downlink shared channel (DL-SCH), resource allocation information of uplink shared channel (UL-SCH), paging information of paging channel (PCH), system information on DL-SCH, and PDSCH. Resource allocation of upper layer control messages such as Random Access Response sent in, set of transmit power control instructions for individual terminals in any terminal group, transmit power control information, Voice over IP Can include activation of. A plurality of PDCCHs may be transmitted within the control area, and the terminal can monitor the plurality of PDCCHs. The PDCCH is transmitted in a combination of one or more consecutive Control Channel Elements (CCEs). CCE is a logical allocation unit used to provide PDCCH at a coding rate based on the state of the radio channel. CCE corresponds to a plurality of resource element groups. The format of the PDCCH and the number of bits available are determined by the correlation between the number of CCEs and the coding rate provided by the CCEs. The base station determines the PDCCH format by the DCI transmitted to the terminal, and adds a cyclic redundancy check (CRC) to the control information. The CRC is masked by an identifier called Radio Network Temporary Identifier (RNTI) depending on the owner or application of the PDCCH. If the PDCCH is for a specific terminal, the cell-RNTI (C-RNTI) identifier of the terminal can be masked to CRC. Alternatively, if the PDCCH is for a paging message, the paging indicator identifier (P-RNTI) can be masked to the CRC. If the PDCCH is for system information (more specifically, the system information block (SIB)), the system information identifier and system information RNTI (SI-RNTI) can be masked to CRC. Random access-RNTI (RA-RNTI) can be masked to CRC to indicate a random access response that is the response to the transmission of the terminal's random access preamble.

FIG. 4 is a diagram showing the structure of the uplink subframe. The uplink subframe can be divided into a control area and a data area in the frequency domain. A physical uplink control channel (PUCCH) including uplink control information is assigned to the control region. A physical uplink shared channel (PUSCH) containing user data is assigned to the data area. In order to maintain the single carrier characteristic, one terminal does not transmit PUCCH and PUSCH at the same time. The PUCCH of one terminal is assigned to a resource block pair (RB pair) in a subframe. The resource blocks belonging to the resource block pair occupy different subcarriers for the two slots. This is called frequency-hopped by the resource block pair assigned to PUCCH at the slot boundary.

(Reference signal (RS))

When a packet is transmitted in a wireless communication system, the transmitted packet is transmitted via a wireless channel, so that signal distortion may occur in the transmission process. In order for the distorted signal to be correctly received on the receiving side, it is necessary to correct the distortion in the received signal using the channel information. In order to know the channel information, a method of transmitting a signal known by both the transmitting side and the receiving side and knowing the channel information according to the degree of distortion when the signal is received through the channel is mainly used. The signal is referred to as a pilot signal or a reference signal.

When transmitting and receiving data using multiple antennas, it is necessary to know the channel status between each transmitting antenna and the receiving antenna in order to receive the correct signal. Therefore, there must be a separate reference signal for each transmitting antenna and, more specifically, for each antenna port.

The reference signal can be divided into an uplink reference signal and a downlink reference signal. Currently, as an uplink reference signal in the LTE system,

i) Demodulation reference signal (DeModulation-Reference Signal; DM-RS) for channel estimation for coherent demodulation of information transmitted via PUSCH and PUCCH,

ii) There is a Sounding Reference Signal (SRS) for the base station to measure the uplink channel quality at different frequencies of the network.

On the other hand, as a downlink reference signal,

i) A cell shared by all terminals in the cell-a specific reference signal (CRS),

ii) Terminals for specific terminals only-specific reference signals (UE-specific Reference Signal),

iii) When PDSCH is transmitted, DM-RS (DeModulation-Reference Signal), which is transmitted for coherent demodulation,

iv) When downlink DMRS is transmitted, a channel state information reference signal (Channel State Information-Reference Signal; CSI-RS) for transmitting channel state information (CSI),

v) MBSFN Reference Signal (MBSFN Reference Signal), transmitted for coherent demodulation of signals transmitted in MBSFN (Multimedia Broadcast Single Frequency Network) mode,

vi) There is a Positioning Reference Signal used to estimate the geolocation of the terminal.

Reference signals can be roughly classified into two types according to their purpose. There is a reference signal of interest for acquiring channel information and a reference signal used for demodulating data. The former has the purpose of the UE to acquire channel information to the downlink, so it must be transmitted over a wide band, and even if the terminal does not receive the downlink data in a specific subframe, its reference signal. Must be received. It is also used in situations such as handovers. The latter is a reference signal sent together with the resource when the base station sends downlink data so that the terminal can measure the channel and demodulate the data by receiving the reference signal. Become. This reference signal must be transmitted in the area where the data is transmitted.

(Modeling of Multiple Antenna (MIMO) System)

FIG. 5 is a configuration diagram of a wireless communication system having multiple antennas.

As shown in FIG. 5 (a), the number N _t transmit antennas, increasing the number of receive antennas and the N _R, unlike the case of using multiple antennas only at the transmitter or receiver, an antenna The theoretical channel transmission capacity increases in proportion to the number of. Therefore, the transmission rate can be improved and the frequency efficiency can be epoch-makingly improved. By increasing the channel transmission capacity, the transmission rate can theoretically be increased by multiplying the maximum transmission rate (Ro) when using a single antenna by the rate increase rate (Ri).

For example, in a MIMO communication system using four transmitting antennas and four receiving antennas, it is theoretically possible to obtain four times the transmission rate as compared with a single antenna system. Since the theoretical capacity increase of multiple antenna systems was proved in the mid-1990s, various techniques for leading to a substantial improvement in data transmission rate have been actively studied to date. In addition, some technologies have already been reflected in various wireless communication standards such as 3G mobile communication and next-generation wireless LAN.

Looking at the trends in research related to multiple antennas to date, research on information theory related to calculation of multiple antenna communication capacity in various channel environments and multiple connection environments, research on radio channel measurement and model derivation of multiple antenna systems, Research is being actively conducted from various viewpoints, such as research on spatiotemporal signal processing technology for improving transmission reliability and transmission rate.

The communication method in the multiple antenna system will be described more concretely by using mathematical modeling. It is assumed that the system has Nt transmitting antennas and Nt receiving antennas.

Explaining the transmission signal, when there are Nt transmission antennas, the maximum information that can be transmitted is NT. The transmitted information can be expressed as follows.

は、送信電力が異なってもよい。それぞれの送信電力を

とすれば、送信電力が調整された送信情報は、次のように表現することができる。 Each transmission information

May have different transmission powers. Each transmission power

Then, the transmission information for which the transmission power has been adjusted can be expressed as follows.

は、送信電力の対角行列

を用いて、次のように表現することができる。 again,

Is the diagonal matrix of transmission power

Can be expressed as follows using.

に重み行列

が適用されて、実際に送信されるＮｔ個の送信信号

が構成される場合を考慮してみよう。重み行列

は、送信情報を送信チャネルの状況などに応じて各アンテナに適切に分配する役割を果たす。

は、ベクトル

を用いて、次のように表現することができる。 Information vector with adjusted transmission power

Weight matrix

Is applied, and Nt transmission signals actually transmitted

Consider the case where is configured. Weight matrix

Plays a role of appropriately distributing transmission information to each antenna according to the status of the transmission channel and the like.

Is a vector

Can be expressed as follows using.

は、ｉ番目の送信アンテナとｊ番目の情報との間の重み値を意味する。

は、プリコーディング行列とも呼ばれる。 here,

Means the weight value between the i-th transmitting antenna and the j-th information.

Is also called a precoding matrix.

はベクトルで次のように表現することができる。 If there are Nr receiving antennas, the received signal is the received signal of each antenna.

Can be expressed as a vector as follows.

と表示することにする。

において、インデックスの順序は受信アンテナインデックスが先で、送信アンテナのインデックスが後であることに留意されたい。 When modeling channels in a multi-antenna radio communication system, the channels can be separated by the transmit / receive antenna index. The channel from the transmitting antenna j to the receiving antenna i

Will be displayed.

Note that the order of the indexes is the receiving antenna index first and the transmitting antenna index later.

On the other hand, FIG. 5B is a diagram showing channels from NR transmitting antennas to receiving antennas i. The channels can be collectively displayed in the form of vectors and matrices. In FIG. 5B, the channels arriving at the receiving antenna i from the total NT transmitting antenna can be represented as follows.

Therefore, all channels arriving from Nt transmitting antennas to Nr receiving antennas can be expressed as follows.

を経た後に白色雑音（ＡＷＧＮ；Ａｄｄｉｔｉｖｅ Ｗｈｉｔｅ Ｇａｕｓｓｉａｎ Ｎｏｉｓｅ）が加えられる。ＮＲ個の受信アンテナのそれぞれに加えられる白色雑音

は、次のように表現することができる。 The actual channel is the channel matrix

White noise (AWGN; Additive White Gaussian Noise) is added after the process. White noise applied to each of the NR receiving antennas

Can be expressed as follows.

Through the mathematical modeling described above, the received signal can be expressed as follows.

の行及び列の数は、送受信アンテナの数によって決定される。チャネル行列

において、行の数は受信アンテナの数ＮＲと同一であり、列の数は送信アンテナの数Ｎｔと同一である。すなわち、チャネル行列

は、行列がＮＲ×Ｎｔとなる。 On the other hand, the channel matrix showing the channel state

The number of rows and columns of is determined by the number of transmitting and receiving antennas. Channel matrix

In, the number of rows is the same as the number NR of the receiving antennas, and the number of columns is the same as the number Nt of the transmitting antennas. That is, the channel matrix

The matrix is NR × Nt.

のランク

は、次のように制限される。 The rank of a matrix is defined as the smallest number of independent rows or columns. Therefore, the rank of the matrix cannot be greater than the number of rows or columns. Channel matrix

Rank

Is restricted as follows:

Another definition of rank can be defined as the number of non-zero eigenvalues when the matrix is Eigenvalue decomposition. Similarly, yet another definition of rank can be defined as the number of non-zero singular values when subjected to singular value decomposition. Therefore, the physical meaning of rank in the channel matrix can be said to be the maximum number that can send different information from each other in a given channel.

In the description of this document, "Rank" for MIMO transmission indicates the number of routes that can transmit signals independently at a specific time point and a specific frequency resource, and "number of layers" is each. Indicates the number of signal streams transmitted over the path. Generally, the transmitting end transmits a number of layers corresponding to the number of ranks used for signal transmission. Therefore, unless otherwise specified, the rank has the same meaning as the number of layers.

(Synchronous acquisition of D2D terminal)

In the following, synchronization acquisition between terminals in D2D communication will be described based on the above description and the existing LTE / LTE-A system. In an OFDM system, if time / frequency synchronization is not achieved, inter-cell interference may make it impossible to multiplex between different terminals in the OFDM signal. It is inefficient for D2D terminals to directly send and receive synchronization signals for synchronization and for all terminals to synchronize individually. Therefore, in a distributed node system such as D2D, a particular node can transmit a representative sync signal and the rest of the UEs can synchronize with it. In other words, for sending and receiving D2D signals, some nodes (at this time, the nodes may be eNBs, UEs, SRNs (also referred to as synchronization reference nodes or synchronization sources)). Can transmit a D2D synchronization signal (D2DSS, D2D Synchronization Signal), and the remaining terminals can synchronize with this to transmit and receive the signal.

Examples of the D2D synchronization signal include a primary synchronization signal (PD2DSS (Primary D2DSS) or PSSS (Primary Synchronization signal)), a secondary synchronization signal (SD2DSS (Secondary D2DSS) or SSSS (Synchronization signal)). The PD2DSS may have a Zadoff-chu sequence of a predetermined length or a structure similar / modified / repeated to the PSS. Also, unlike DL PSS, other Zadofuchu root indexes (eg 26,37) can be used. The SD2DSS may have an M-sequence or a structure similar / modified / repeated to the SSS. If the terminal synchronizes from the eNB, the SRN becomes the eNB and the D2DSS becomes the PSS / SSS. Unlike DL's PSS / SSS, PD2DSS / SD2DSS follow the UL subcarrier mapping scheme. FIG. 6 shows a subframe through which a D2D sync signal is transmitted. PD2DSCH (Physical D2D synchronization channel) is the basic (system) information that the terminal must know first before transmitting and receiving D2D signals (for example, information related to D2DSS, duplex mode (DM), TDD). It may be a (broadcast) channel through which UL / DL configuration, resource pool related information, D2DSS related application type, subframe offset, broadcast information, etc.) are transmitted. The PD2DSCH may be transmitted on the same subframe as the D2DSS or on a subsequent subframe. DMRS can be used for demodulation of PD2DSCH.

The SRN may be a node that transmits D2DSS and PD2DSCH (Physical D2D synchronization channel). The D2DSS may be in the form of a particular sequence, and the PD2DSCH may be in the form of a sequence that indicates specific information, or in the form of a codeword after undergoing predetermined channel coding. Here, the SRN may be an eNB or a specific D2D terminal. In the case of partial network coverage or out of network coverage, the terminal can be an SRN.

The D2DSS may be relayed for D2D communication with an out-of-coverage terminal in the situation as shown in FIG. The D2DSS may also be relayed via multiple hops. In the following description, relaying the synchronization signal includes not only directly AF relaying the synchronization signal of the base station, but also transmitting a D2D synchronization signal in a different format according to the reception time of the synchronization signal. It is a concept. By relaying the D2D synchronization signal in this way, the terminal within the coverage and the terminal outside the coverage can directly communicate with each other.

(D2D resource pool)

FIG. 8 shows an example of UE1 and UE2 that perform D2D communication, and the D2D resource pool used by them. In FIG. 8A, the UE means network equipment such as a terminal or a base station that transmits and receives signals according to a D2D communication method. The terminal can select a resource unit corresponding to a specific resource in a resource pool which means a set of a series of resources, and transmit a D2D signal using the resource unit. The receiving terminal (UE2) receives a resource pool configuration (configured) to which the UE 1 can transmit a signal, and can detect the signal of the UE 1 in the pool (pool). Here, the resource pool can be notified by the base station when UE1 is within the connection range of the base station, and can be notified by another terminal or in advance when it is outside the connection range of the base station. It may be determined by a defined resource. Generally, a resource pool is composed of a plurality of resource units, and each terminal can select one or a plurality of resource units and use them for its own D2D signal transmission. The resource unit may be as illustrated in FIG. 8 (b). With reference to FIG. 8B, it can be seen that the entire frequency resource is divided into NFs, the total time resource is divided into NTs, and a total of NF * NT resource units are defined. Here, it can be said that the resource pool is repeated with the NT subframe as a cycle. In particular, one resource unit may appear periodically and repeatedly as shown in the figure. Alternatively, in order to obtain a diversity effect in the time or frequency domain, the index of the physical resource unit to which one logical resource unit is mapped may change with time in a predetermined pattern. In such a structure of resource units, the resource pool may mean a set of resource units that can be used for transmission by a terminal that intends to transmit a D2D signal.

Resource pools can be subdivided into various types. First, it can be classified according to the contents of the D2D signal transmitted in each resource pool. For example, the contents of the D2D signal may be divided, and a separate resource pool may be configured for each. The contents of the D2D signal may include SA (Scheduling assistance; SA), a D2D data channel, and a Discovery channel. SA includes the position of resources used for transmission of the D2D data channel that the transmitting terminal follows, MCS (modulation and coding scene) and MIMO transmission method required for demodulation of other data channels, TA (timing advance), and the like. It may be a signal containing the information of. This signal can also be multiplexed and transmitted with D2D data on the same resource unit. In this case, the SA resource pool is a pool of resources in which SA is multiplexed and transmitted with D2D data. Can mean. As another name, it can also be called a D2D control channel (control channel) or a PSCCH (physical sidelink control channel). The D2D data channel (or PSCH (Physical sidelink shared channel)) may be a pool of resources used by the transmitting terminal to transmit user data. When SA is multiplexed and transmitted together with D2D data on the same resource unit, only the D2D data channel in the form excluding SA information can be transmitted in the resource pool for the D2D data channel. In other words, the REs that were used to transmit SA information on the individual resource units in the SA resource pool can still be used to transmit D2D data in the D2D data channel resource pool. The discovery channel may be a resource pool for messages that allow a transmitting terminal to send information such as its own ID so that neighboring terminals can discover itself.

Even when the contents of the D2D signal are the same, different resource pools can be used depending on the transmission / reception attribute of the D2D signal. For example, even if the same D2D data channel or discovery message is used, the transmission timing determination method of the D2D signal (for example, whether it is transmitted at the time of receiving the synchronization reference signal or whether it is transmitted by applying a certain TA) or Resource allocation method (for example, whether the eNB specifies the transmission resource of the individual signal to the individual transmission UE or the individual transmission UE selects the individual signal transmission resource independently in the pool), signal format (for example, each D2D signal). Depending on the number of symbols occupied by one subframe, the number of subframes used to transmit one D2D signal), the strength of the signal from the eNB, the strength of the transmission power of the D2D UE, etc., the resource pools will be different from each other again. It may be classified. For convenience of explanation, in D2D communication, the method in which the eNB directly instructs the transmission resource of the D2D transmission UE is Mode1, the transmission resource area is preset, the eNB specifies the transmission resource area, and the UE directly selects the transmission resource. The method of doing so will be called Mode2. In the case of D2D discovery, it is called Type2 when the eNB directly instructs the resource, and Type1 when the UE directly selects the transmission resource in the preset resource area or the resource area specified by the eNB.

(Sending and receiving SA)

The mode 1 terminal can transmit SA (or D2D control signal, SCI (Sidelink Control Information)) with the resource configured by the base station. In the mode 2 terminal, the resources used for D2D transmission are composed of base stations. Then, the SA can be transmitted by selecting the time frequency resource from the configured resources.

The SA period can be defined as shown in FIG. Referring to FIG. 9, the first SA cycle can be started in a subframe separated from the specific system frame by a predetermined offset (SAOffsetIndicator) indicated by the upper layer signaling. Each SA cycle can include a SA resource pool and a subframe pool for D2D data transmission. The SA resource pool can include from the first subframe of the SA cycle to the last subframe of the subframes instructed to transmit SA by the subframe bitmap (saSubframeBitmap). In the mode 1, the resource pool for D2D data transmission is a subframe actually used for data transmission by applying T-RPT (Time-resource pattern for transmission or TRP (Time-resource pattern)). Can be determined. As shown in the figure, when the number of subframes included in the SA cycle excluding the SA resource pool is larger than the number of T-RPT bits, the T-RPT can be repeatedly applied, and the last applied T. -RPT can be applied by truncating the number of remaining subframes. The transmitting terminal transmits at the position where the T-RPT bitmap is 1 in the instructed T-RPT, and one MAC PDU transmits four times at a time.

FIG. 10 illustrates an operation method for DCC (distributed congestion control) defined in 802.11p. The DCC measures the CBP (channel PHY percentage) by each terminal, and if the load is above a certain level, it changes the state (Rexed, Active, Restrive), and when the state is changed, the transmission power (tx) is changed. Not only power) but also Phy rate, sensing threshold, and message transmission frequency (message transmission frequency) are changed at the same time. In addition, the inter-message reception time (inter message reception time) changes greatly depending on the state change. Such a DCC has a disadvantage that it is difficult to grasp which parameter affects the performance because too many parameters change at once each time the state changes. In DCC, congestion measurement (measures the occupied energy of the channel in a certain period of time, if it is above the critical value / limit value, it is judged to be busy, and the percentage of busyness (percentage) within a specific time window (time window). ) Is above or below a certain criticality, the state is changed.) Therefore, a congestion mismatch phenomenon may occur between the terminals. For example, the terminal group A is judged to be busy and the channel access is reduced, but the terminal group B adjacent to the terminal group A is judged to be idle and has a high channel access parameter because it is not used by the group A. In this case, a performance inequality phenomenon may occur between the terminal groups A and B (the specific terminal group continuously uses the active state, and the other specific terminal groups continuously use the restrictive state). Alternatively, a phenomenon may occur in which the specific area terminal switches between the active state and the restrictive state (or the relaxed state and the active state) depending on the time.

In the following, a method of solving the disadvantages of DCC (congestion measurement of terminals, performance unevenness phenomenon, etc. described above) by V2X communication and controlling interference in a densely populated area will be described. The terms used in the following description are:

F-node: A device that controls or assists V2X communication at a fixed position is called a fixed node. The F-node may be in the eNB form or the UE form. F-node can also be called RSU (rod node unit).

V-UE: A wireless terminal mounted on a moving vehicle or a UE used by a driver of a moving vehicle shall be referred to as a V-UE.

P-UE: A terminal carried by a person traveling on the road is called a pedestrian UE (P-UE). A person may be traveling by bicycle or other means of transportation (Segway, electric wheel), and usually refers to a terminal that is less mobile than a V-UE.

A UE behavior can be described as operating in another behavior when all or part of the following i) to vi) parameters are different from each other.

i) MCS: Modulation and coding or RB size

ii) Tx power: Transmission power of the terminal

iii) Message generation period: The period in which the terminal sends a message (may be the period in which the message is reserved. When the terminal uses semi-persistent transmission, the resource is reserved. The period to be used can be indicated. Unless otherwise explained below, the SPS period (SPS period) is included.).

iv) Number of iterations (Repetition number): Number of retransmissions for one MAC PDU of the terminal

v) Sensing threshold: A critical / limit value such as RSSI or RSRP when the terminal determines the channel idle / busy. Specifically, it may be related to the sensing method, and when sensing, if the measured value measured by the terminal is higher than the critical value / limit value, it is determined to be busy, and vice versa, it is determined to be idle.

vi) Conflict window (CW) size: If the terminal knows in advance that the channel is free or determines that it is idle from other information, the terminal sets the backoff counter (backoff counter) to 1 in the conflict window. It can be reduced in increments. In other words, the counter is initially set to CW size, decrements by 1 each time the channel becomes idle, and transmits when the counter reaches 0.

viv) Resource pool (pool): Separate resource pools can be used depending on the type of UE, the message type (message type), and the geo information (geo-information) (position, speed, direction, etc.) of the UE.

(UE behavior signaling of F-node)

F-node physically applies common measurements and / or UE behaviors (MCS / MCS range, transmission power, message generation cycle, number of iterations (range), sensing thresholds, all or part of competing window size) to the V-UE. It is possible to set the V-UE that signals the layer or the upper layer signal and receives the signal to operate in the behavior specified by the F-node. The designation for such UE behaviors may vary from region to region, for example, the resource pool or available resource set in the resource pool is set differently depending on the geolocation information (location, speed, direction, etc.) of the terminal. At this time, the F-node can signal the UE behavior used in each resource area (resource pool, resource set, resource subset in the resource pool) to the terminal with a physical layer or upper layer signal. When there is no F-node in the vicinity, the UE behavior (for example, MCS, RB size, etc.) used for each resource pool may be predetermined.

The UE behavior signaled by the F-node may be determined from the measured value of the V-UE. More specifically, the V-UE can signal the measured value and / or the status (or UE behavior) of the measurement to the F-node with a physical layer or upper layer signal. The F-node can calculate a common measurement value in the corresponding area from the status or measurement value from the peripheral UE. The UE behavior can then be determined and signaled from this calculated common measurement. The F-node may average the measured values received from the UE instead of the UE behavior and signal it to the V-UE with a physical layer or upper layer signal. Measured values and / or UE behavior related parameters (MCS, transmission power, message generation cycle (or) via backhaul or radio channel between F-nodes to set common behaviors between F-nodes. , SPS period (SPS period), number of iterations (retransmission), sensing threshold, conflict window size) may be shared in whole or in part.

The F-node can specify a specific MCS used by the UE. Alternatively, F-node can specify the range of MCS available in the area. At this time, the MCS or the range of the MCS may be used in the specific geolocation information (position, velocity, direction, etc.) and / or the resource pool as described above. For example, the MCS range used by the UE at a speed below the critical / limit value may be signaled in the upper layer. When there is no F-node in the vicinity, the UE behavior (for example, MCS, RB size, etc.) used for each resource pool may be predetermined. This method can be useful for setting the MCS low in consideration of the relative speed with the receiving terminal when the terminal moves at high speed. If the terminal decides the MCS independently by the speed, the MCS is decided without considering the relative speed with the receiving terminal, but F-node preliminarily determines the average relative speed between the terminals in the corresponding area. It can be seen that the transmission / reception performance between terminals can be improved by determining the optimum MCS or MCS range for transmission / reception of terminals in the corresponding region of F-node.

The F-node can transmit critical / critical velocity (range) information using the RRC signaled UE behavior by upper layer signaling. In this case, the UE sets the RRC-signaled UE behavior-related parameters (MCS / MCS range, transmission power, message generation cycle, number of iterations (range), sensing threshold, conflict window size) within the RRC-signaled speed range. Can be used / applied. Alternatively, terminals whose speed is above a certain level may be signaled to the terminals in whole or in part, such as the transmission power used by those terminals, the MCS RB size, and the like. More generally, the network (F-node) signals the terminal with a physical layer or upper layer signal under what conditions the terminal sets which transmission parameter, or the upper and / or lower limits of the transmission parameter. be able to. Here, each condition may be the geoposition information of the terminal, the speed, the load of the resource area (the ratio of the occupied resources among the resources in the specific resource area (details will be described later), and the like.

On the other hand, different UE behavior values may be signaled depending on the message size and priority. For example, in the case of an event tricker message, set a higher repetition value or a higher sensing critical value / limit value than the periodic message to make it more frequent and faster. It can be set to transmit signals. In the case of a periodic message that is transmitted at a long period (also, such a long period message may include security information regarding a later short period message and the like) and is transmitted at a short period. It may be set to a different UE behavior than the message sent in.

When the terminal changes the UE behavior according to the geoposition information of the terminal described above, not only the MCS and RB sizes but also the transmission power can be changed.

On the other hand, the information returned by the terminal to the F-node can include the ratio of the occupied resources among the resources in the specific resource area. Here, the ratio of occupied resources can be calculated / calculated by the following three methods. The first is a method based on SA decoding, in which data resources associated with SA can be found using SA decoding, and the ratio of resources occupied in the entire data resource area. Can be calculated by the terminal. The second is an energy sensing method, in which when the energy (RSSI or RSRP (of RS signal)) measured in a specific resource unit exceeds a certain criticality, the resource can be considered to be occupied and the entire data resource area. The ratio of resources occupied in can be calculated. The third is a method based on both SA decoding and energy sensing. All of the average measured energy amount in the specific resource area, the average RSSI / RSRP / RSRQ between D2D terminals, the rate at which packets are dropped without being transmitted, and the average decoding success / failure probability in the specific resource area. Alternatively, a part of the signal can be signaled by a physical layer or upper layer signal. At this time, different information can be signaled in the transmission mode (mode 1 or mode 2) of the terminal for each resource area. Further, for that purpose, the F-node can signal the D2D terminal with an instruction to report the measurement result in the specific resource area by the physical layer or the upper layer signal. Alternatively, all or part of the D2D terminal transfers the measurement information to the F-node (with a predetermined or network-instructed probability, a predetermined or network-instructed cycle) as a physical layer or upper layer signal. Can be signaled with. Such information can be collected by F-node and others and used for operations such as setting transmission parameters of terminals and changing resource area resetting Mode 1 / Mode 2. In addition, such information can be directly utilized by the terminal for reference to its own transmission parameter setting (transmission power, resource size (RB size, number of retransmissions), MCS, etc.). When the terminal receives an instruction to report such information, the terminal can periodically or aperiodically report the related information to the F-node by a physical layer or upper layer signal.

On the other hand, the parameters of the UE behavior may be predetermined in the absence of the F-node. At this time, different conflict parameters can be used depending on the message type. For example, different parameters can be used depending on the priority of the message. Then, the priority of the message can be event trigger message> periodic message having security information> periodic message having no security information. The priority for each message may be determined by the upper layer. Here, the event trigger message is a message sent when a specific event occurs, and is a message for notifying an accident, danger, or the like. A periodic message having security information (or a long-period periodic message) is a periodic message transmitted in a relatively long period, and includes security information of a short-period message transmitted later. be able to. A periodic message without security information (or a short periodic message) is a periodic message transmitted in a relatively short period, and is a message frequently transmitted after a long period message. May be good. For example, a message with a higher priority may have a higher access probability (CW may be set smaller than a message with a lower priority, or a sensing critical value / limit value may be set higher (more). Specifically, the terminal compares the priority of the message sent by itself with the priority of the message occupying the resource, sets a higher sensing critical value in the case of a higher priority, and sets the resource. Can be made to have a higher chance of trying to use. For this purpose, the F-node can signal the priority sensing critical value to the terminal with a physical layer or upper layer signal), iterative. The number of times can be set large). All or part of the parameters (MCS / MCS range, transmission power, message generation cycle, number of iterations (range), sensing threshold value, conflict window size) may be set to be different depending on the priority. In such parameter setting based on the priority, the priority may be predetermined depending on the message type and the content.

(UE behavior signaling of UE)

The UE (or V-UE) sets all or part of its behavior, measurements, or parameters related to determining the behavior to SA (control signal) or MAC header (or MAC CE) of the data. Other upper layer fields), or can be included in control signals transmitted with data or transmitted by piggyback. In this case, behaviors and measurements can be shared between UEs without F-node and can be used as a reference for determining their own behaviors. The UE's MAC header (or MAC CE or other higher layer field) (or MAC CE) or SA is all or part of the parameters such as MCS, transmit power, message generation cycle, number of iterations, sensing thresholds, conflict window size, etc. Can be included. For example, by transmitting the SA or MAC header (or MAC CE or other upper layer field) containing the MCS, message generation cycle, transmission power, CW size, and sensing critical value / limit value, which peripheral terminal is used. You can decide your own behavior by referring to whether it works with such a behavior.

Of the UE behavior signaling of the UE described above, the message generation cycle may mean SPS (semi persistent scheduling) in which the current resource allocation is maintained after Xms, but depending on this value, it is also present after Xms. It can be interpreted in the sense of maintaining the resource allocation of. The SPS cycle value may be included in the SA and transmitted, and the SA cycle (or message generation cycle) interval or number regarding how many SA cycles (or message generation cycles) after that the current resource allocation is maintained is determined. It may be included in the SA and transmitted.

Specifically, the UE can select the information bit related to the resource reservation included in the control information and transmit the control information through the channel through which the control information is transmitted. Here, the information bit can simultaneously indicate whether or not the UE reserves a resource, and when the resource is reserved, the resource position. That is, the method of indicating the section length for instructing the reservation (reservation) of the resource in the next transmission and the method of indicating whether or not to make a reservation in the next cycle can be embodied in combination. For example, if the UE does not reserve a resource, 0 is selected as the information bit value, and if the UE reserves a resource, a value other than 0 is selected as the information bit value. The UE can transmit data after a time interval corresponding to the selected non-zero value. As another example, it is possible to indicate that the 2-bit state is included in the SA and transmitted, the bit state 00 does not make a reservation, and 01, 10, and 11 indicate the SPS section length. As another example, the terminal can set the SPS section up to 100, 200, 300, ..., 1000 ms, and at this time, the 4-bit field can be included in the SA and transmitted. At this time, 00 is the next. It can be shown that the resource is not reserved in the cycle of.

From the standpoint of the receiving UE with reference to FIG. 11, the control information is received (S1101) via the channel through which the control information is transmitted, and the information bits related to the resource reservation included in the control information are confirmed. Can be done. As described above, the information bit indicates whether or not the UE that transmitted the control information reserves the resource, and if the resource is reserved, the resource position is simultaneously indicated, so that the receiving UE is the information bit related to the resource reservation. Whether or not the value is 0 can be determined (S1102). If the information bit is 0, the UE can predict / assume / assume that the UE that transmitted the control information did not reserve the resource (S1103). If the information bit is a value other than 0, the UE reserves the same frequency resource after the time interval corresponding to the information bit by the UE that transmitted the control information, and the data is obtained after the time interval corresponding to the information bit. Can be predicted / assumed / assumed to be transmitted (S1104). At this time, if the UE is a UE that receives data corresponding to the control information, the UE can decode the data with the same frequency resource as the frequency resource for which the data was received after the time interval. If the UE is a UE that does not receive the data corresponding to the control information, the UE can exclude the frequency resource for which the data was received after the time interval when selecting the resource for transmission.

In the above description, the value selected as the information bit may be the one allowed by the cycle-related parameters transmitted by the upper layer signaling by the F-node. That is, the information bits associated with the resource reservation that the UE selects when transmitting data may follow the UE behavior signaling of the F-node. More specifically, the first message can be transmitted on a time-frequency resource. When the UE has to send a second message related to the first message, it sends the second message in the same frequency resource area of the time-frequency resource as the frequency resource area after a predetermined time from the time-frequency resource. Can be done. Here, the predetermined time is determined by the bit selected by the UE from among the plurality of bits (information bit related to the resource reservation described above), and the bit that can be selected by the UE among the plurality of bits is the upper layer signaling. It may be tolerated by the cycle-related parameters transmitted in. Then, whether or not the above tolerance is allowed can be indicated by a bitmap by upper layer signaling. For example, periodic information that can be used in 10 states up to 100, 200, ..., 1000 can be signaled to the terminal in the form of a bitmap. For example, in the case of 1010101010, it can be indicated that only the cycles of 100, 300, 500, 700 and 900 can be used by the terminal. Cycle-related parameters can be transmitted from the UE-related F-node (Fixed node). In this way, resource reservation can be appropriately controlled by F-node, but in this case, it is possible to prevent the UE from indiscriminately reserving resources after a long time. Extremely, the F-node can always set only a specific cycle (for example, 100 ms) to the SPS cycle used by the terminal. This is because the F-node is set so that all terminals send messages in the cycle.

In addition to the selection of information bits related to resource reservation, the UE behavior signaling of F-node can control the operation of various UEs as follows. For example, when the second message is a retransmission of the first message, the second message may be transmitted within the number of retransmissions. At this time, the number of retransmissions may be the one transmitted to the UE by the upper layer signaling. Further, MCS within the range indicated by the upper layer signaling can be used for the transmission of the first message. The MCS can be used when the UE is at a subcritical speed or within a specific speed range, and the subcritical speed or specific speed range may be transmitted by higher layer signaling.

The control information and the resources for the data corresponding to the control information may always be selected at the same time. That is, both SA and data are reserved, and both SA / data can be reselected at the time of selection. Although the SA and the data are transmitted including whether or not the data is reserved in the SA, the reservation / selection can be performed for both the SA and the data. In this method, once the SA and the data are determined by sensing, if it is confirmed that a collision has occurred in either the SA or the data, the resource selection of both the SA and the data is selected. )I do. That is, in this method, when the SA and the data are reserved, both the SA and the data resource are maintained, and it is possible to stably estimate how much interference will occur to other terminals. Furthermore, SA and data can be reserved at the same time to prevent unnecessary reselection, which enables stable measurement of terminal interference.

SA and data reservation may be instructed separately. In SA, it can be transmitted including information indicating all the reservation (SPS or message generation) cycle of SA and data and whether or not the data is reserved. In this method, whether or not to maintain SA resource transmission in the next SPS cycle in SA and whether or not to maintain the presence or absence of data resource transmission are included in SA for transmission. By including the resource selection and maintenance information most flexibly, this method can directly indicate whether or not to reselect when one or both of the SA and the data collide. For example, if a SA resource conflicts with another UE, the SA is released, the SA reselects at the next transmission, and the data retains the reservation and undergoes a separate reselection process. Not performed. That is, in this case, in the next message transmission, an indicator indicating whether or not to maintain the resource allocation of the current SA cycle is included in the SA and one bit for each data and transmitted, and the SA and the SA are transmitted by this indicator. Notify peripheral terminals whether or not each data is reserved.

The SA can indicate whether to reserve data by selecting resources randomly, according to a predetermined hopping pattern, or by sensing each time. This is a method of transmitting data including whether or not to reserve the data in SA. In this method, SA can use a method of selecting and transmitting SA resources for each data transmission (for each SA period). For example, a specific SA resource index linked to the SA ID can be selected for each SA cycle and used for SA transmission. Alternatively, a method can be used in which SA resources are randomly selected and transmitted for each data transmission. Alternatively, a method of selecting SA resources by sensing for each data transmission can be used. Even if SA resource allocation using sensing is performed, if the same SA resource is selected each time, a continuous collision with a specific UE with similar sensing results may occur, which is prevented. Therefore, a method of randomly selecting from SA resources other than resources whose energy is less than a certain criticality or resources occupied in advance by another UE, or a method of selecting resources by UE ID can be used.

On the other hand, the SA may be transmitted for each data transmission according to a predetermined hopping pattern (hopping pattern for solving the half-duplex problem), but at this time, the hopping pattern may be transmitted by sensing. You can determine the best resource. At this time, when measuring the energy of SA, the SA resource position where SA retransmission occurs can be regarded as one SA resource group, and the measured values can be averaged to measure the SA resource. Each terminal knows the SA hopping pattern for each SA resource in advance in the SA pool, makes measurements for each SA resource, averages the measurements for each SA resource group according to the hopping pattern for each SA resource, and takes the energy in it. SA can be transmitted by randomly selecting an SA resource from the SA resource group in which is X% or less. In the extreme, the SA resource group with the lowest energy can be selected. Such an operation is a method in which the advantages of a method in which the terminal simply randomly determines the SA resource and a method in which the SA resource is determined by energy sensing are combined. When the SA resource depends on energy measurement, there is a disadvantage that the half-duplex problem of SA cannot be completely solved between terminals. When the SA resource is randomly determined for each data transmission, the data resource is determined based on sensing. However, a phenomenon may occur in which the data reception performance is deteriorated due to in-band emission while SA transmission occurs randomly. When the optimum energy is grasped and transmitted while solving the half-duplex problem of SA and maintained during a constant data transmission cycle, there is an advantage that data sensing can be performed stably.

On the other hand, the data reservation cycle (reservation period) and the SA reservation cycle may be set to different cycles. For example, the data can be reserved during 1000 ms, and the SA can be reserved every 200 ms. ..

On the other hand, when the terminal measures the interference of peripheral terminals, it may be performed by SA decoding, the energy of the data may be measured, or the energy of SA may be measured. The network can signal the terminal with a physical layer or upper layer signal as to which of these methods is used for sensing. When configured to use each scheme, the network can signal the relevant critical / limit parameters to the terminal. For example, the network can instruct a particular region or terminal to perform SA decoding-based sensing. Alternatively, the network can instruct a particular terminal to use both SA decoding and data energy measurements. The terminal can select a resource whose energy is less than a certain criticality from the remaining resources except the resource occupied through SA decoding. Alternatively, the network can be instructed to make resource selections using only the energy measurements of the data. In this case, the terminal can perform resource selection / reselection based on the energy measurement of the data.

(Measurement and signaling of F-node)

The F-node can make a measurement and inform the terminal of the measured value, or the F-node can signal a UE behavior based on the measurement of the terminal. In this case, in the DCC where the terminal performs the measurement, the problem of separately determining the current channel status at the time when the terminal performs the measurement and / or the position of the terminal performing the measurement can be complemented. For example, the F-node collects the result of the measurement performed by the terminal, and the behavior of the terminal in the corresponding area can be determined by the F-node. More specifically, the following method can be considered.

The F-node can measure the peripheral congestion and signal it to the V-UE. The F-node measures its own RSSI or the busyness of the channel (eg, measuring the RSRP of the RS transmitted by the UE and exceeding a predetermined criticality or time to exceed the criticality within a particular window). It can be signaled to the V-UE and / or P-UE with a physical layer or upper layer signal. The terminal does not use the value measured by the F-node as it is, but shares the measured value with the peripheral F-node by a wired backhaul (for example, an X2 interface or a separate wired backhaul) or a wireless interface (air interface). Can signal it to the terminal. That is, each F-node averages the measured value or UE behavior (or UE state) with the surrounding F-node (determines a common behavior in the case of behavior / UE state) and signals it to the terminal. can do.

The terminal can perform a weighted average from the measurement of each F-node so that the peripheral terminals have some common behavior. For example, when two F-nodes (F-nodes 1 and 2) are observed and the signal reception strength from each F-node is A, B [Watt], the UE is (A * F-node). It is possible to determine 1's measurement + B * F-node 2's measurement) / (A + B) and smooth the measured value. The weighted average of the two measured values is not limited to the weighted average, and the weighted average of the F-nodes in which the signal strength above a certain criticality is received can be performed.

The terminal can also determine the final behavior by using the value measured by itself instead of using the value signaled by F-node as it is. It is not preferable that the measurement of the terminal is not reflected at all in that the actual measurement is not reflected. The rate at which the terminal measurement is reflected can be signaled by the network or F-node with a physical layer or upper layer signal. For example, it may vary depending on the density of F-node in a specific area. When the density of F-node is high, a relatively high weight is applied to the measured value signaled by F-node, and when the density of F-node is low, the measured value signaled by F-node is applied. Apply a low weight.

(How to determine UE behavior of UE)

When the message transmission and / or reception frequency (message generation cycle) is simply controlled by load or channel congestion, the specific terminal may have a long message-to-message reception and / or transmission time. As described above, if the frequency of past message transmission and / or reception by the specific terminal is below a certain level, a method of raising this again can be considered. That is, the current behavior can be determined by referring to the past behavior in order to prevent the performance deterioration of a specific terminal, instead of determining its own behavior in consideration of the load and congestion of the current channel.

For example, in the case of a terminal having a long message generation cycle during a specific time interval, a rule can be set to set a short message generation cycle for transmission. As another example, a terminal whose transmission power is previously set to AdBm during a specific time interval can be ruled to transmit in BdBm after the corresponding time. This behavior can be applied to sending a message, but it can also be applied to receiving a message. When a specific type of message cannot be received within a certain period of time, it can be used for increasing the reception window length of the message or setting a short message monitoring cycle to increase the reception rate.

(P-UE monitoring method)

For P-UE, constant monitoring can be a burden due to battery problems. Therefore, in the case of the P-UE, the operation of waking up intermittently and monitoring can be performed, but at this time, the following specific operations can be considered.

First, the transmit or receive pool for the P-UE only may be signaled by the F-node with physical or upper layer signals or may be predetermined. On the other hand, the resource pool for such a P-UE can be set to a relatively long cycle in consideration of the battery consumption of the P-UE (for example, 1 second, 100 ms interval). It can be assumed that the P-UE does not transmit in the transmit pool for the P-UE only, and the P-UE can transmit after sensing only in the P-UE transmit pool. At this time, it may occur that no UE transmits in a part of the initial pool of the P-UE. Therefore, the transmit pool for the P-UE may be configured with all or part of the UE behavior parameters different from the V-UE. Alternatively, the P-UE and V-UE may be set so that all or part of the UE behavior parameters differ from the V-UE depending on the type of terminal regardless of the pool. In order to prevent no P-UE from transmitting at the beginning, the P-UE randomly determines the resource and signals a part of the initial pool of the P-UE (or the resource used by the P-UE). Can be set to be transmitted, or a predetermined sequence or code word can be set to be transmitted at a random time position so that other P-UEs can grasp the approximate degree of congestion. On the other hand, the P-UE may not be able to transmit SLSS every SLSS transmission cycle due to battery saving operation. To that end, the P-UE is the closest SLSS resource in front of the resource pool for the P-UE, or the nearest N SLSS resources in front of the resource pool for the P-UE, and / or the P-UE. SLSS transmission can be performed with the SLSS resource in the resource pool set for. Further, the SLSS transmitted by the P-UE may be classified into the SLSS transmitted by the V-UE, its format (format) or ID in advance, or may be instructed in the PSBCH field. Alternatively, the SLSS transmitted by the P-UE may be transmitted using the ID or PSBCH indicated by the eNB or RSU.

Second, if the transmit pool for P-UEs only is aligned with all P-UEs, the P-UEs will not be able to hear each other's signals due to the half duplex constraint. Problems can occur. Alternatively, in-band radiation between P-UEs may prevent other UEs from smoothly receiving. In order to solve this, the transmission pool of the P-UE is divided into N sub-pools (or the period (period) of the transmission pool of the P-UE transmitted by the specific P-UE group is divided in advance. Propose a way to send in different subpools. Subpools other than the subpools that they send are monitored to get a rough idea of the degree of congestion. The subpool to be transmitted by the P-UE may be randomly determined, and the value obtained by taking the modulor N of the P-UE ID can be used as the seed value for determining the subpool of the P-UE. Alternatively, the F-node is a physical layer or upper layer signal and can signal the seed value of the subpool index / or subpool selection to be transmitted by the P-UE. Alternatively, the pool selection method is determined in advance based on the signal strength of the specific F-node or the signal strength of the UE, and a rule can be set to use the pool when the specific conditions are satisfied. At this time, in order to prevent continuous transmission in the same UE group and subpool, the selection of the subpool can be hopped at random or by the SA ID of the UE every cycle (period).

Third, when the P-UE wakes up (intermittently wakes up) and receives the message in a longer cycle than the V-UE, but cannot receive the V2X message in the section where it wakes up and receives the message. Or, if a relatively important message (for example, a security message (security message)) cannot be received, the user can wake up and try to receive the message. For example, when the density of the vehicle terminal is very high, the transmission cycle of the V-UE can be lengthened, or the message can be transmitted a larger number of times. At this time, it is assumed that the operation of waking up 100 ms in 1 second and receiving the V-UE signal is performed. However, in this case, the density of the V-UE may be too high to receive the message accurately within 100 ms. In this case, the P-UE wakes up for another 100 ms and tries to receive the message, and if the same message as the previous 100 ms message tries to combine, or receives a new message from the vehicle terminal again. It will be possible. The extension of the wake-up time due to the reception rate of such a P-UE may be predetermined, and the wake-up time cycle, the section length, and the length of the additional wake-up time due to the occurrence of congestion may be all or all depending on the network. Part of it may be configured. Here, in order to distinguish between the case where the message could not be received and the case where the message was not sent from the beginning, the specific SA or data is measured as having a high energy or RS power value, but the corresponding channel. A case where data reception fails can be assumed as such a case. Not only in such a case, the message is displayed when the energy sensing or SA is read in advance and the decoding is performed with the expectation that the data will be received in the corresponding resource area, but the CRC fails (file). It can be regarded as a case where the data is transmitted but the reception fails. If the message reception ratio or the number of messages that could not be received is equal to or higher than a certain criticality, the wake-up time is further extended to further attempt to receive V2X messages. For that purpose, the type of message to be received is explicitly signaled to other terminals using SA, or the physical layer format is set differently (DMRS sequence, CS, OCC are set differently depending on the type of message). ), An explicit physical layer indicator can be included in a certain area of the data RE and transmitted.

Fourth, if the P-UE fails to receive a particular type of message during the wake-up time window, it can further wake up and receive. For example, if the security message cannot be received among the event trigger message and the periodic message, the user can wake up and try to receive the message.

Fifth, if the P-UE that receives in the predetermined wake-up window cannot receive the message in the window within a certain period of time (however, at this time, it cannot be heard because there is no message, and it interferes. In order to distinguish from the case where the single energy level is above a certain criticality but cannot be received (at this time, the energy level critical value / limit value may be predetermined, and the energy level critical value / limit value may be determined in advance. It may be configured by a network.))) Can be set to wake up and listen more frequently by shortening the wake-up cycle of the P-UE. At this time, the cycle may be predetermined or may be configured by the network, and the terminal may be set by the network or predetermined specific conditions (for example, the number of messages received during the wake-up time, the reception rate, etc.). If the condition is less than a certain criticality), the wake-up cycle can be set short to further attempt to receive the V2X message.

Sixth, the length of the window in which the P-UE wakes up may be changed, but in order to reduce the battery consumption of the P-UE below a certain level, the cycle in which the P-UE wakes up is also the surrounding situation. It may be set differently depending on the situation of the terminal. For example, if the P-UE receives a message within 500 ms for some reason, the P-UE wakes up may be set longer (eg, 5 seconds) in consideration of the P-UE's battery drain. can. If congestion occurs in the peripheral V-UE and the message generation cycle is corrected to a long cycle, the P-UE wakes up once and cannot receive all the signals of the peripheral V-UE terminals. Therefore, in such a case, it is preferable to align the message reception window in which the P-UE wakes up and listens to the message generation cycle of the V-UE. However, in this case, since the battery consumption of the P-UE may increase excessively, the message reception cycle of the P-UE is increased together to alleviate the burden on the battery consumption of the P-UE.

Seventh, the message transmission and / or reception cycle and the message transmission and / or reception window size may be changed depending on the mobility of the P-UE. For example, the P-UE may be a P-UE that moves fast by bicycle or other means of transportation. In such a case, the message transmission and / or reception window / cycle may be set differently depending on the state and situation of the P-UE. For example, when the P-UE recognizes the situation of getting in the car or is instructed by the upper layer, the message generation similar to the V-UE may perform the transmission / reception operation even if the P-UE is present. can. As another example, when the situation where the P-UE is riding a bicycle is recognized or indicated by an upper layer signal, the P-UE wakes up more frequently than the existing P-UE and listens to the messages of the surrounding V-UEs. , The operation of receiving the V-UE message in a longer time can be performed.

Eighth, in the case of the mobility and status of the P-UE described above and the mode change indicated by the upper layer, the corresponding UE uses a different resource pool from the transmission pool used by the existing P-UE and V-UE. Can be used. For example, when notifying the P-UE that the vehicle has been boarded in the upper layer, even if the terminal is the P-UE, the resource pool and behavior of the V-UE can be followed. That is, in V2X operation, the behavior of the UE is not a characteristic unique to the terminal but is variable by being indicated by an upper layer signal, and such a change in the behavior of the terminal can be changed depending on the state of the terminal. Optimal operation can be performed according to the situation of the terminal. For such an operation, a method of recognizing the state of the terminal in the upper layer (for example, application layer) and sending an indicator for reflecting this in the operation of the physical layer or the MAC layer is proposed. Alternatively, for such an operation, the network determines the behavior level of the terminal in advance, and when the network is notified of the status of the terminal and the interference information of the surroundings, the network informs the terminal. You can instruct it to work with a particular behavior. Or, when the network signals the terminal to the terminal in advance with a physical layer or upper layer signal according to the environment treated by the terminal, or after determining in advance, the terminal becomes the corresponding situation. It can operate with the behavior specified by the network. For example, when a P-UE gets in a vehicle or a bicycle, the terminal recognizes such a situation, reports the measurement to the network, and the network configures the behavior in the situation. If so, the terminal will operate with the behavior set for the measurement and situation.

On the other hand, depending on the transmitting UE type and message type, the receiving UE may or may not need to hear, but in order to distinguish this by the physical layer and reduce the battery consumption of the receiving terminal, the UE Type and / or message type is explicitly included in the SA ID and SA for transmission, DMRS sequence is set differently, and instructions indicating the UE type and / or message type in a part of the data area. Suggest a method to send including children. For example, the P-UE may not need to hear the signals of other P-UEs, so that each UE sends to the SA including an indicator indicating whether it is a P-UE or a V-UE. Can be done. This may be further extended to send the directives separately depending on the message type and packet type. For example, some messages may be for the P-UE and some messages may be for the V-UE, even if they are messages transmitted by the V-UE. Therefore, in order to prevent the receiving terminal from performing unnecessary reception operations depending on the type of message, we propose a method of dividing the resource area proposed above and / or a method of distinguishing this by the physical layer. Both methods can be embodied in combination or individually. If the message type and the UE type are defined for each resource area, the terminal that does not have to receive the entire resource area can significantly reduce the power consumption. Alternatively, even if the resource areas are not distinguished, when the SA of the SA pool is received, if the SA of the UE that does not need to be heard is received, the data decoding is not performed, so that the power consumption of the terminal is consumed. It has the advantage of reducing.

On the other hand, the P-UE may not be able to receive all the messages transmitted by the V-UE, such as a security message, which are transmitted at a relatively long cycle. For example, the V-UE sends a periodic message every 100ms, but the security message is sent every 500ms, and the P-UE wakes up for a while and listens only to the message for 100ms due to battery drain problems. There is a possibility that you may not receive the security message at this time. In such a case, we propose a method in which the eNB or RSU broadcasts the security message of the peripheral V-UE. The eNB or RSU can signal the P-UE with a V-UE security message with a separate physical layer or upper layer signal. Even if the P-UE cannot receive the security message of all V-UEs during the time of waking up, the message of the V-UE can be interpreted by using the message signaled by the eNB or RSU.

On the other hand, all or part of the proposed operation is not limited to the operation of the P-UE, and can be extended and applied to the V-UE. Conversely, the operation of the V-UE can be extended and applied to the P-UE.

Since an example of the proposed method described above can be included as one of the methods for embodying the present invention, it is a clear fact that it can be regarded as a kind of proposed method. Further, the above-mentioned proposed methods may be embodied independently, or may be embodied in the form of a combination (or merger) of some of the proposed methods. Information indicating whether or not to apply the proposed method (or information regarding the rules of the proposed method) should be notified to the terminal by the base station by a predefined signal (for example, a physical layer signal or an upper layer signal). Rules may be defined in.

(Device Configuration According to Examples of the Present Invention)

FIG. 12 is a diagram showing a configuration of a transmission point device and a terminal device according to an embodiment of the present invention.

Referring to FIG. 12, the transmission point device 10 according to the present invention can include a receiving device 11, a transmitting device 12, a processor 13, a memory 14, and a plurality of antennas 15. The plurality of antennas 15 mean a transmission point device that supports MIMO transmission / reception. The receiving device 11 can receive various signals, data, and information on the uplink from the terminal. The transmission device 12 can transmit various signals, data and information on the downlink to the terminal. The processor 13 can control the overall operation of the transmission point device 10.

The processor 13 of the transmission point device 10 according to the embodiment of the present invention can process the necessary items in each of the above-described embodiments.

The processor 13 of the transmission point device 10 also has a function of arithmetically processing the information received by the transmission point device 10, the information to be transmitted to the outside, and the like, and the memory 14 calculates the arithmetically processed information and the like for a predetermined time. It can be stored and can be replaced with components such as buffers (not shown).

Next, referring to FIG. 12, the terminal device 20 according to the present invention can include a receiving device 21, a transmitting device 22, a processor 23, a memory 24, and a plurality of antennas 25. The plurality of antennas 25 mean a terminal device that supports MIMO transmission / reception. The receiving device 21 can receive various signals, data, and information on the downlink from the base station. The transmission device 22 can transmit various signals, data, and information on the uplink to the base station. The processor 23 can control the overall operation of the terminal device 20.

The processor 23 of the terminal device 20 according to the embodiment of the present invention can process the necessary items in each of the above-described embodiments.

The processor 23 of the terminal device 20 also has a function of arithmetically processing information received by the terminal apparatus 20, information transmitted to the outside, and the like, and the memory 24 stores the arithmetically processed information and the like for a predetermined time. It can be replaced with components such as buffers (not shown).

As for the specific configuration of the transmission point device and the terminal device as described above, the matters described in the various examples of the present invention described above are applied independently, or two or more examples are applied at the same time. The duplicated content is omitted for clarity.

Further, in the description of FIG. 12, the description of the transmission point device 10 can be similarly applied to the repeater device as the downlink transmission subject or the uplink reception subject, and the description of the terminal device 20 can be applied to the downlink reception subject. Alternatively, it can be similarly applied to a repeater device as an uplink transmission subject.

The above-described embodiment of the present invention can be embodied by various means. For example, the embodiments of the present invention can be embodied by hardware, firmware, software, or a combination thereof.

In the case of hardware implementation, the method according to the embodiment of the present invention is one or more ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processor), DSPD (Digital Signal Processing Device). It can be embodied by a device), an FPGA (Field Programgate Array), a processor, a controller, a microprocessor, a microprocessor and the like.

In the case of realization by firmware or software, the method according to the embodiment of the present invention can be embodied in the form of a device, procedure or function that executes the function or operation described above. The software code can be stored in a memory unit and driven by a processor. The memory unit is located inside or outside the processor and can exchange data with the processor by various already known means.

Detailed descriptions of preferred embodiments of the invention disclosed above have been provided so that those skilled in the art can embody and implement the invention. Although the above description has been made with reference to preferred embodiments of the present invention, it is understood that skilled artisans in the art can make various modifications and modifications to the present invention without departing from the realm of the present invention. can. For example, those skilled in the art can use the method of combining the configurations described in the above-described embodiment. Accordingly, the present invention is not intended to limit itself to the embodiments presented herein, but to provide the broadest scope consistent with the principles and novel features disclosed herein.

The present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention. Therefore, the above detailed description should not be construed in a restrictive manner in any respect and should be considered as an example. The scope of the invention should be determined by the reasonable interpretation of the appended claims, and any changes within the equivalent scope of the invention are within the scope of the invention. The present invention is not intended to limit itself to the embodiments presented herein, but to provide the broadest scope consistent with the principles and novel features disclosed herein. In addition, claims that are not explicitly cited from the scope of claims can be combined to form an example, or can be included as a new claim by amendment after filing.

The embodiments of the present invention as described above are applicable to various mobile communication systems.

Claims (3)

V2X a way to receive the data by the wireless communication system first User Equipment (UE),
A step of receiving control information including information bits from the second UE by the first UE, and
By the first UE, from the second UE, and a step it receives the first data on the frequency resources have you to the subframe N based on the control information,
The information bit set to zero signals that the frequency resource is not reserved by the second UE.
The information bit set to a non-zero time interval (I), and informs both the previous SL frequency resources are reserved in the sub-frame N + I,
Prior Symbol first UE, receives the second data from the second UE said have you to the subframe N + I on the frequency resources, methods. The method according to claim 1, wherein the resource for the control information and the resource for the data corresponding to the control information are always selected at the same time. And the control information, and data corresponding to the control information is transmitted in embodiments of the FDM, The method of claim 1.

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